[jeffbro]

Can you help me? I have a 98 chevy cavalier, while driving my rpm's jump and
Down 500 rpm at a time. I was told it was a vss sensor. I went to a parts store and
They said the vehicle takes two sensors. I put in one, the other looks like a magnetic pick up. I can't find out where it fits. The tech said the car has two vss sensors. The car still jumps 500 or so rpm's while driving. I'm stumped.
Can you help me. Thanks, jeffbro

[CaptainRich]

Can you help me? I have a 98 chevy cavalier, while driving my rpm's jump and
down 500 rpm at a time. I was told it was a vss sensor. I went to a parts store and
they said the vehicle takes two sensors. I put in one, the other looks like a magnetic pick up. I can't find out where it fits. The tech said the car has two vss sensors. The car still jumps 500 or so rpm's while driving. I'm stumped.
Can you help me. thanks, jeffbro

I can't imagine there being a correlation between the VSS (Vehicle Speed Sensor), which is for the speedometer display, and the engine RPM jumping. Unless there is some kind of feedback or wires crossed or some kind of electrical interference. Is your vehicle equipped with a tachometer? Or are you hearing the RPM change?
And that vehicle's transmission has more that one sensor, but only one is the VSS.
What the "tech" may have meant is that there are two possible sensors, depending on which automatic transmission you have: 3 speed or 4 speed. There is only one possible VSS for a manual transmission.

[this8384]

When you say that your RPMs "jump while driving", are you saying that they are constantly fluctuating? I agree with Rich that your vehicle speed shouldn't affect the RPM reading; have you had a diagnostic scan done to see if there are any codes stored in the computer?